i. Calcium carbonate (Lime stone) is treated with dil. hydrochloric acid. ii. Aluminium is treated with dil. hydrochloric acid.

Question

Explain the following reactions giving their balanced chemical equations:

i. Calcium carbonate (Lime stone) is treated with dil. hydrochloric acid.

ii. Aluminium is treated with dil. hydrochloric acid.

iii. Magnesium is treated with hydrochloric acid.

iv. Hydrogen peroxide is decomposed in the presence of manganese dioxide (MnO₂).

v. Ethyl alcohol is treated with acidified potassium dlchromate.

vi. Hydrogen gas is passed over black copper oxide.

Answer 1

i. When calcium carbonate (lime stone) is treated with dil. hydrochloric acid, carbon dioxide gas is formed.

ii. When aluminium is treated with dilute hydrochloric acid, hydrogen gas is liberated.

iii. When magnesium is treated with hydrochloric acid, hydrogen gas is liberated.

iv. When hvdrogen peroxide is decomposed in the presence of manganese dioxide (MnO₂), water and oxygen are formed.

v. When ethly alcohol is treated with acidified potassium dichromate, acetic acid is formed. This is oxidation reaction.

vi. When hydrogen gas is passed over black copper oxide, a reddish coloured layer of copper is formed.